Colin Kaepernick #7 of the San Francisco 49ers returns to the sideline after turning the ball over for a touchdown against the St. Louis Rams at the Edward Jones Dome on December 2, 2012 in St. Louis, Missouri. The Rams beat the 49ers 16-13 in overtime.

Photo: Dilip Vishwanat, Getty Images

Colin Kaepernick #7 of the San Francisco 49ers returns to the...

Image 2 of 36

San Francisco 49ers kicker David Akers, left, and St. Louis Rams' Janoris Jenkins react after Akers missed a 51-yard field goal attempt in overtime of an NFL football game, Sunday, Dec. 2, 2012, in St. Louis. The Rams won 16-13.

Photo: Jeff Roberson, Associated Press

San Francisco 49ers kicker David Akers, left, and St. Louis Rams'...

Image 3 of 36

San Francisco 49ers quarterback Colin Kaepernick, right, tries to toss the ball to teammate Ted Ginn as St. Louis Rams' Quintin Mikell (27) defends during the second half of an NFL football game on Sunday, Dec. 2, 2012, in St. Louis. The play was ruled a fumble, recovered by Rams' Janoris Jenkins who took it in for a touchdown.

Photo: Seth Perlman, Associated Press

San Francisco 49ers quarterback Colin Kaepernick, right, tries to...

Image 4 of 36

San Francisco 49ers wide receiver Ted Ginn is unable to pick up a fumble by quarterback Colin Kaepernick during the second half of an NFL football game against the St. Louis Rams, Sunday, Dec. 2, 2012, in St. Louis. Rams' Janoris Jenkins recovered the fumble and took it in for a touchdown.

Photo: Seth Perlman, Associated Press

San Francisco 49ers wide receiver Ted Ginn is unable to pick up a...

Image 5 of 36

Frank Gore (21) of the 49ers is pulled down after a short gain by James Laurinaitis (55) of the St. Louis Rams during the NFL game between the San Francisco 49ers vs the St. Louis Rams at the Edward Jones Dome in St. Louis Missouri. (Danny Reise / SPECIAL TO THE CHRONICLE)

Photo: Danny Reise, SFC

Frank Gore (21) of the 49ers is pulled down after a short gain by...

Image 6 of 36

Head coach of the 49ers Jim Harbaugh during the NFL game between the San Francisco 49ers vs the St. Louis Rams at the Edward Jones Dome in St. Louis Missouri. (Danny Reise / SPECIAL TO THE CHRONICLE)

Photo: Danny Reise, SFC

Head coach of the 49ers Jim Harbaugh during the NFL game between...

Image 7 of 36

Colin Kaepernick (7) of the 49ers sends a pass to Bruce Miller (49) of the 49ers during the NFL game between the San Francisco 49ers vs the St. Louis Rams at the Edward Jones Dome in St. Louis Missouri. (Danny Reise / SPECIAL TO THE CHRONICLE)

Photo: Danny Reise, SFC

Colin Kaepernick (7) of the 49ers sends a pass to Bruce Miller (49)...

Image 8 of 36

Patrick Willis (52) of the 49ers during the NFL game between the San Francisco 49ers vs the St. Louis Rams at the Edward Jones Dome in St. Louis Missouri. (Danny Reise / SPECIAL TO THE CHRONICLE)

Photo: Danny Reise, SFC

Patrick Willis (52) of the 49ers during the NFL game between the...

Image 9 of 36

San Francisco 49ers quarterback Colin Kaepernick looks to throw during the second quarter of an NFL football game Sunday, Dec. 2, 2012, in St. Louis.

Photo: Seth Perlman, Associated Press

San Francisco 49ers quarterback Colin Kaepernick looks to throw...

Image 10 of 36

San Francisco 49ers quarterback Colin Kaepernick is sacked for a 7-yard loss by St. Louis Rams outside linebacker Jo-Lonn Dunbar (58) and defensive end William Hayes, right, during the first quarter of an NFL football game Sunday, Dec. 2, 2012, in St. Louis.

Photo: Seth Perlman, Associated Press

San Francisco 49ers quarterback Colin Kaepernick is sacked for a...

Image 11 of 36

St. Louis Rams quarterback Sam Bradford (8) talks to teammates in the huddle during the second quarter of an NFL football game against the San Francisco 49ers Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

St. Louis Rams quarterback Sam Bradford (8) talks to teammates in...

Image 12 of 36

San Francisco 49ers running back Frank Gore (21) scores on a 1-yard run during the first quarter of an NFL football game against the St. Louis Rams Sunday, Dec. 2, 2012, in St. Louis.

Photo: Seth Perlman, Associated Press

San Francisco 49ers running back Frank Gore (21) scores on a 1-yard...

Image 13 of 36

ST. LOUIS, MO - DECEMBER 2: Lance Kendricks #88 of the St. Louis Rams catches a pass against Donte Whitner #31 of the San Francisco 49ers at the Edward Jones Dome on December 2, 2012 in St. Louis, Missouri.

Photo: Dilip Vishwanat, Getty Images

ST. LOUIS, MO - DECEMBER 2: Lance Kendricks #88 of the St. Louis...

Image 14 of 36

ST. LOUIS, MO - DECEMBER 02: Cornerback Carlos Rogers #22 of the San Francisco 49ers tackles tight end Lance Kendricks #88 of the St. Louis Rams during the game at the Edward Jones Dome on December 02, 2012 in St. Louis, Missouri.

Photo: David Welker, Getty Images

ST. LOUIS, MO - DECEMBER 02: Cornerback Carlos Rogers #22 of the...

Image 15 of 36

ST. LOUIS, MO - DECEMBER 2: Colin Kaepernick #7 of the San Francisco 49ers avoids getting tackled by William Hayes #95 of the St. Louis Rams at the Edward Jones Dome on December 2, 2012 in St. Louis, Missouri.

Photo: Dilip Vishwanat, Getty Images

ST. LOUIS, MO - DECEMBER 2: Colin Kaepernick #7 of the San...

Image 16 of 36

Patrick Willis (52) of the 49ers during the NFL game between the San Francisco 49ers vs the St. Louis Rams at the Edward Jones Dome in St. Louis Missouri. (Danny Reise / SPECIAL TO THE CHRONICLE)

Photo: Danny Reise, SFC

Patrick Willis (52) of the 49ers during the NFL game between the...

Image 17 of 36

Chris Givens (13) of the St. Louis Rams breaks free from a tackle by Carlos Rogers (22) of the 49ers during the NFL game between the San Francisco 49ers vs the St. Louis Rams at the Edward Jones Dome in St. Louis Missouri. (Danny Reise / SPECIAL TO THE CHRONICLE)

Photo: Danny Reise, SFC

Chris Givens (13) of the St. Louis Rams breaks free from a tackle...

Image 18 of 36

Colin Kaepernick (7) of the 49ers under pressure runs to to the side line during the NFL game between the San Francisco 49ers vs the St. Louis Rams at the Edward Jones Dome in St. Louis Missouri. (Danny Reise / SPECIAL TO THE CHRONICLE)

Photo: Danny Reise, SFC

Colin Kaepernick (7) of the 49ers under pressure runs to to the...

Image 19 of 36

Head coach of the 49ers Jim Harbaugh watching the 49ers kick the first extra point during the NFL game between the San Francisco 49ers vs the St. Louis Rams at the Edward Jones Dome in St. Louis Missouri. (Danny Reise / SPECIAL TO THE CHRONICLE)

Photo: Danny Reise, SFC

Head coach of the 49ers Jim Harbaugh watching the 49ers kick the...

Image 20 of 36

San Francisco 49ers running back Frank Gore runs for a 23-yard gain during the first quarter of an NFL football game against the St. Louis Rams Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers running back Frank Gore runs for a 23-yard gain...

Image 21 of 36

San Francisco 49ers inside linebacker NaVorro Bowman (53) takes up his position as St. Louis Rams quarterback Sam Bradford (8) prepares for the play during the first quarter of an NFL football game Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers inside linebacker NaVorro Bowman (53) takes up...

Image 22 of 36

St. Louis Rams quarterback Sam Bradford (8) hands off to running back Steven Jackson during the first quarter of an NFL football game against the San Francisco 49ers Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

St. Louis Rams quarterback Sam Bradford (8) hands off to running...

Image 23 of 36

San Francisco 49ers running back Frank Gore runs for a 23-yard gain during the first quarter of an NFL football game against the St. Louis Rams Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers running back Frank Gore runs for a 23-yard gain...

Image 24 of 36

San Francisco 49ers quarterback Colin Kaepernick warms up before the start of an NFL football game between the St. Louis Rams and the San Francisco 49ers Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers quarterback Colin Kaepernick warms up before...

Image 25 of 36

St. Louis Rams running back Steven Jackson warms up before the start of an NFL football game between the St. Louis Rams and the San Francisco 49ers Sunday, Dec. 2, 2012, in St. Louis.

Photo: Seth Perlman, Associated Press

St. Louis Rams running back Steven Jackson warms up before the...

Image 26 of 36

San Francisco 49ers quarterback Colin Kaepernick drops back to pass during the first quarter of an NFL football game against the St. Louis Rams Sunday, Dec. 2, 2012, in St. Louis.

Photo: Jeff Roberson, Associated Press

San Francisco 49ers quarterback Colin Kaepernick drops back to pass...

Image 27 of 36

San Francisco 49ers running back Frank Gore, left, scores on a 1-yard run past St. Louis Rams linebacker Josh Hull during the first quarter of an NFL football game on Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers running back Frank Gore, left, scores on a...

Image 28 of 36

San Francisco 49ers outside linebacker Aldon Smith laughs as he warms up before the start of an NFL football game between the St. Louis Rams and the San Francisco 49ers Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers outside linebacker Aldon Smith laughs as he...

Image 29 of 36

San Francisco 49ers running back Frank Gore (21) gets past St. Louis Rams free safety Quintin Mikell on his way to a 23-yard gain during the first quarter of an NFL football game on Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers running back Frank Gore (21) gets past St....

Image 30 of 36

San Francisco 49ers quarterback Colin Kaepernick scrambles during the first quarter of an NFL football game against the St. Louis Rams Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers quarterback Colin Kaepernick scrambles during...

Image 31 of 36

Tattoos are seen on the arm of San Francisco 49ers quarterback Colin Kaepernick as he warms up before the start of an NFL football game between the St. Louis Rams and the San Francisco 49ers Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

Tattoos are seen on the arm of San Francisco 49ers quarterback...

Image 32 of 36

San Francisco 49ers quarterback Alex Smith smiles as he warms up before the start of an NFL football game between the St. Louis Rams and the San Francisco 49ers Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers quarterback Alex Smith smiles as he warms up...

Image 33 of 36

San Francisco 49ers outside linebacker Ahmad Brooks takes up his position during the first quarter of an NFL football game against the St. Louis Rams Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers outside linebacker Ahmad Brooks takes up his...

Image 34 of 36

San Francisco 49ers quarterback Colin Kaepernick throws during the first quarter of an NFL football game against the St. Louis Rams Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers quarterback Colin Kaepernick throws during the...

Image 35 of 36

San Francisco 49ers linebacker Tavares Gooden takes up his position during the first quarter of an NFL football game against the St. Louis Rams Sunday, Dec. 2, 2012, in St. Louis.

Photo: Tom Gannam, Associated Press

San Francisco 49ers linebacker Tavares Gooden takes up his position...

Image 36 of 36

St. Louis Rams quarterback Sam Bradford drops back to pass during the first quarter of an NFL football game against the San Francisco 49ers Sunday, Dec. 2, 2012, in St. Louis.

As Steve Young observed last week, the NFL is a "big-boy league" and it's not always going to be easy or glory-filled for a young player. After two remarkable games as a starter, Colin Kaepernick felt the other side of what the NFL offers. Frustration. Pain. Defeat.

In a strange, error-filled 16-13 overtime loss to the Rams on Sunday, Kaepernick frequently looked like an inexperienced and overwhelmed player. And he wanted to blame himself for the key mistakes.

"It was my fault all the way," Kaepernick said.

That's not true. The fault for the loss belongs with many people, starting with head coach Jim Harbaugh who approved a crazy, risky call in a tight game. The pitch play that went awry, and led to the Rams' only touchdown, was a strange bit of arrogance in a game with no room for error.

And that's what the 49ers have now: no margin for error. With the loss, their record is 8-3-1. Their cause was helped by Seattle's victory over Chicago, allowing the 49ers to maintain their hold on the second seed in the NFC, a position that would give them a first-round bye and home-field advantage in the divisional round.

The 49ers have a half-game lead over both Chicago and Green Bay. Still, the 49ers have back-to-back difficult road games, a Sunday nighter in New England on Dec. 16 and a matchup with Seattle on Dec. 23.

They will, presumably, be relying on Kaepernick to win those games. Harbaugh said that he "feels" that Kaepernick will start next Sunday. But the head coach has to know that the questions will continue to come if Kaepernick has another rough outing. That's the situation Harbaugh has created, with his unprecedented benching of a starting quarterback who was playing well for a team that seems, at least at times, Super Bowl-caliber.

Teams will prepare for Kaepernick and take a page from what St. Louis head coach Jeff Fisher did Sunday. The Rams had an excellent game plan, bringing heavy pressure on Kaepernick and taking away his deep options. Kaepernick was sacked three times and was forced out of bounds several times.

"They did have a lot of good calls," Kaepernick said. "It seemed like they were in the right defense for things we were trying to do."

The game was almost as odd as the tie at Candlestick three weeks earlier, except that the 49ers were motivated from the opening kick. They started strongly with a first-quarter touchdown run by Frank Gore and more impressive passing from Kaepernick.

But in the second half, the 49ers' offense stalled. Backed into his end zone, Kaepernick scrambled to avoid pressure and threw the ball away. He was called for intentional grounding, and the Rams were awarded a safety - their first points of the game.

Kaepernick argued that he was outside the tackle box and that the ball made it to the line of scrimmage, even though it was out of bounds. Replays showed that Kaepernick was right.

Harbaugh couldn't challenge. Referee Carl Cheffers said after the game that, because it is a penalty, "none of that is subject to review."

What's two measly points? A lot, it turns out. The 49ers padded their lead to 10-2 with David Akers' 23-yard field goal. With less than five minutes to play, the 49ers again took possession deep in their territory.

On 3rd-and-3 from their 17, the 49ers called an inexplicably risky play: a pitchout to infrequently targeted Ted Ginn Jr. Kaepernick sailed the ball high over Ginn's head. Janoris Jenkins recovered it and carried it into the end zone for a touchdown. A two-point conversion tied the score.

Harbaugh didn't overrule Greg Roman's play call and was second-guessing it later, saying, "I would love to have that one back. ... It was too risky of a play to call at that time."

It's the coach's job to protect a young player and put him in the best situation - but Kaepernick blamed himself.

"I gave up those points on the scoreboard for the Rams," Kaepernick said. "It's 100 percent my fault."

He tried to make things right late in the fourth quarter. He took off downfield, running for 50 yards, assisted by great blocks from Frank Gore and Bruce Miller. But, later in the drive, Kaepernick made a mental error when he ran out of bounds on third down. That stopped the clock and, after Akers made a go-ahead field goal, the Rams had enough time to get downfield and force overtime on Greg Zuerlein's 53-yard field goal.

In overtime, the 49ers made curious choices again, playing conservatively before settling for a 51-yard attempt by Akers, who had appeared on the injury report last week and said he has been nursing a pelvis injury for a while. Not surprisingly, he missed the attempt. Zuerlein made a 54-yard field goal for the win.

It's December and we still can't be sure what to make of the 49ers. They have played poorly every third game this season, losing to Minnesota and to the Giants, then tying and now losing to the Rams. In between those outings, they have looked like the best team in the league.

The NFL is a big-boy league, and every week is going to be tough and unpredictable. As Alex Smith could have - and probably has - told Kaepernick, there are going to be rough days.

Kaepernick's rough days are coming down the stretch, with little margin for error.